Remove old traces of typings.

In the commit akveo/ng2-admin@e7fca6d4, we moved to @types for TypeScript typings.

It remains some traces in the documentation. This commit remove them.

docs/contents/articles/002-installation-guidelines/index.md

@@ -29,11 +29,6 @@ npm install --global webpack
 npm install --global webpack-dev-server
 ```
 
-* typings
-```bash
-npm install --global typings
-```
-
 * typescript
 ```bash
 npm install --global typescript
@@ -59,7 +54,7 @@ This will setup a working copy of ng2-admin on your local machine.
 
 **Note**: If you have any issues after the installation, additionally run the following:
 ```bash
-typings install && bower install
+bower install
 ```
 ## Running local copy
 

docs/contents/articles/012-project-structure/index.md

@@ -53,7 +53,6 @@ ng2-admin/
    ├──tslint.json                * typescript lint config
    ├──typedoc.json               * typescript documentation generator
    ├──tsconfig.json              * config that webpack uses for typescript
-   ├──typings.json               * our typings manager
    ├──package.json               * what npm uses to manage it's dependencies
    ├──bower.json                 * DEPRECATED - moving to npm as primary package manager for all dependenties
    └──.bowerrc                   * DEPRECARD - temporary bower configuration